Yeah..all four of my dogs are mild mannered in public. Fi can get a little uppity with the right dog but overall they are all chill. I was at a match this weekend, standing and watching some of the groups, and Fiona was passed out on her side in the grass. Definitely needs a "dog person" owner. She had been a bit of a challenge as a pup, I think as she hit 5-6mo I swore off having any other ACD puppies . I've figured out her quirks and how to manage/deal/fix them and all is good now. Even Skye is reserved/aloof in public, quiet and happy, calm...at home she is quite the opposite and is very very insistent with her "wants".
Had a young girl that wanted an ACD or an Aussie to do agility with... she went with an Aussie pup, and I know she is struggling controlling the dog (he is a little reactive, drags her around, kind of spooky). She did do basic obedience with him but I don't think it was quite the dream dog her and her family expected.
I had a husband and wife approach me at our last show asking about Aussies, how much they cost (always a bad sign), and how hard they are to live with. I was polite but hammered home that 90% of the time they're not a breed for beginners. I'm pretty sure I was able to dissuade them, but they seemed pretty smitten with Cohen.